"""
Auxiliary file
==============================================
"""

import numpy as np

def evaluate(X, params=[7, 0.1]):
    """Non-monotonic Ishigami-Homma three parameter test function"""

    a = params[0]
    b = params[1]

    Y = np.sin(X[:, 0]) + a * np.power(np.sin(X[:, 1]), 2) + \
        b * np.power(X[:, 2], 4) * np.sin(X[:, 0])

    return Y
